Novel phosphorus compounds

ABSTRACT

Compounds of formula (I), wherein each of R and R′ are independently selected from hydrogen, a hydroxyl group, a carboxyl group, an alkyl, aryl or alkaryl group or a hydroxy or carboxy substituted alkyl, aryl or alkaryl group, provided that R R′, together have a total of less than 23 carbon atoms, R″ may either be hydrogen or a CHR═CR 1  group or be selected from the same categories as R′″; R′″ is a group, or polymeric chain comprising from 1 to 100,000 groups, said group or groups being derived form at least one ethylenically unsaturated compound wherein the double bond is activated by an adjacent electron withdrawing group, and n is greater than 1 are novel, are useful corrosion inhibitors and are valuable intermediates in preparing telomers for use in water treatment.

[0001] The present invention concerns novel phosphorus compounds whichmay be obtained by a process comprising reacting an acetylenic compoundwith hypophosphorous acid, or its salts.

[0002] The reaction of acetylene with hypophosphorous acid in thepresence of perbenzoic acid or tertiary butyl peroxide to give1,2-diphosphino ethane was described by Nifantev et al in Zh ObstichKhim Vol 56 Pp 773-781 (1986). The Authors state that the reactionproduct with two organic groups attached to the phosphorus was notobtained. This clearly implies that no polymeric material could beobtained by the method described.

[0003] Kneller et al (U.S. Pat. No. 5,647,995) describe the preparationof homologues and substituted analogues of 1,2-diphosphino ethane byreacting hypophosphorous acid with higher alkynes and substitutedalkynes. The preparation of mono and diphosphinates is described but nocopolymers of acetylene with hypophosphorous acid containing more than 2phosphorus atoms per molecule were prepared or described. Kneller et alalso describe reacting the mono or diphosphinates with unsaturatedcarboxylic acids such as acrylic acid to make telomers which are usefulin water treatment as scale inhibitors of calcium carbonate scale.

[0004] We have now discovered that contrary to the teaching of Nifantevet al, the reaction between hypophosphorous acid and alkynes can be usedto prepare polymers with more than two alkylene groups and more than twophosphorus atoms. Such polymers are particularly useful as corrosioninhibitors and/or as intermediates, for the synthesis of a variety ofwater treatment agents, fire retardants, tanning agents and biocides.The reaction with acetylene proceeds with difficulty and requiresrelatively extreme conditions to obtain a high degree of polymerisation,however higher alkynes and substituted alkynes, containing 3 to 25carbon atoms, react more readily.

[0005] In a first embodiment, the present invention provides a compoundof the formula (1):

[0006] wherein:

[0007] R and R′ are each independently selected from hydrogen, ahydroxyl group, a carboxyl group, an alkyl, aryl or alkaryl group or ahydroxy—or carboxy—substituted alkyl, aryl or alkaryl group, providedthat R and R′ together have a total of less than 23 carbon atoms;

[0008] R″ is hydrogen, or CHR═CR′ or selected from the same categoriesas R′″;

[0009] R′″ is a group, or a polymeric chain comprising from 1 to 100,000groups, each said group being derived from at least one ethylenicallyunsaturated compound wherein the double bond is activated by an adjacentelectron-withdrawing group;

[0010] X is hydrogen or a cation or an alkyl group; and n is greaterthan 1.

[0011] According lo another embodiment our invention provides a methodof producing a compound of the type described in theimmediately-preceding paragraph, said method comprising thecopolymerisation of hypophosphorous acid or a salt or ester of said acidwith an acetylenic compound of formula RC≡CR′, where R and R′ (which maybe the same or different) are each selected from hydrogen, a hydroxygroup, a carboxy group, an alkyl, aryl or alkaryl group or a hydroxy—orcarboxy—substituted alkyl, aryl or alkaryl group having from 1 to 22carbon atoms, so that R and R′ together have from 0 to 25 carbon atoms,whereby in said formula (I) R″ and R′″ are each hydrogen and the averagevalue of n is greater than one.

[0012] According to a further embodiment the invention provides the useof said polymer as a corrosion inhibitor and/or scale inhibitor in thetreatment of a water system.

[0013] According to a fourth embodiment the invention provides a methodof preparing a telomer which comprises reacting said polymer with anethylenically unsaturated compound wherein the double bond is activatedby an adjacent electron withdrawing group.

[0014] According to a fifth embodiment the invention provides a methodof treating potentially corrosive and/or scale forming water systemswhich comprises adding a corrosion or scale inhibiting proportion ofsaid polymer and/or said telomer to said system.

[0015] Preferably the reaction is carried out in a solvent capable ofdissolving both reagents. Depending on the acetylenic compound, thesolvent may be water or a polar organic solvent, typically in admixture,with aqueous hypophosphorous acid, eg: ethanol, dioxan, a water miscibleglycol or glycol ether such as ethylene glycol or ethylene glycolmonomethyl ether, ketones such as acetone or methyl isobutyl ketone, ordiethyl formamide. The reaction also requires an initiator, which maypreferably be a source of free radicals such as hydrogen peroxide,sodium persulphate, azo compounds such as azoisobutyronitrile, organicperoxides or a source of ultraviolet or ionising radiation.

[0016] The acetylenic compound may be acetylene itself, which may, forexample, be bubbled through a solution of hypophosphorous acid or itssalts. However good yields of higher polymers are not readily obtainablefrom acetylene itself due to its volatility, which may requireconditions such as high pressure which are inconvenient or potentiallyhazardous. We therefore prefer to use less volatile acetyleniccompounds, and especially alkynes and hydroxy or carboxy alkynes with 3to 25 carbon atoms, such as propargyl alcohol, acetylene dicarboxylicacid or an alkyne having, preferably 3 to 20 carbon atoms such as1-butyne, 2-butyne or a C₁₂₋₁₄ alkyne. It is also within the scope ofthe invention to use cyclic alkynes, eg: in which R and R1 in theforegoing formula together with the acetylenic group form a cycloalkynering.

[0017] The reaction may be carried out at an elevated temperature, eg:40 to 100° C. preferably 50 to 70° C.

[0018] The proportions may be substantially equal or may comprise asmall, eg: up to 20%, stoichiometric excess of either reagent butpreferably of the hypophosphite. The reaction may be carried out underelevated, atmospheric or, preferably, reduced pressure.

[0019] The hypophosphorous reagent may be the acid or a soluble saltsuch as sodium, potassium or ammonium or an ester such as the methyl,ethyl or isopropyl ester.

[0020] The present invention further provides a polymer, of the formula(II):

[0021] where X is hydrogen or a cation or alkyl group, n is from 1.05 to100, e.g.: 1.2 to 50, preferably 1.5 to 25 especially 2 to 20 moreespecially 3 to 15.

[0022] It is also possible to obtain polymers containing, e.g.:

[0023] units, especially when R is a bulky group e.g.: a phenyl group.

[0024] According to a further embodiment, the invention provides acompound comprising a telomer of the formula (III):

[0025] where X, R, R′ have the same significance as before, at least oneR^(v), in each monomer unit is a hydroxy, carboxy, sulpho, phosphono,amido, aceto, or aryl group or halogen, and each other R^(v) isindependently selected from hydrogen, and C₁₋₄ alkyl, carboxyl, sulpho,phosphono, hydroxyl groups, and carboxy, sulpho, phosphono or hydroxysubstituted C₁₋₄ alkyl groups, (a+b) is from 5 to 200 and n is greaterthan 1.

[0026] The novel telomers may be prepared by co-polymerising saidpolymers with at least one monomer of formula R₂ ^(v)═C R₂ ^(v) whereR^(v) has the same significance as before, in the presence of a freeradical initiator.

[0027] Preferred monomers include acrylic acid, fumaric acid, maleicacid, vinylsulphonic acid, vinyl phosphonic acid, vinylidenediphosphonic acid, methacrylic acid, itaconic acid, aconitic acid,mesaconic acid, citraconic acid, crotonic acid, isocrotonic acid,angelic acid, tiglic acid and the water soluble salts of the aforesaidacids.

[0028] The telomers may additionally comprise proportions, usually minorproportions, of styrene, styrene-p-sulphonic acid,2-acrylamido-2-methylpropane sulphonic acid, vinyl alcohol, vinylacetate, vinyl chloride and/or acrylamide. The relative proportions ofoligomer or polymer and the monomer may range from 1:1 to 1:1000,preferably from 1:5 to 1:500 especially 1:10 to 1:100, eg: 1:15 to 1:50.The reaction is preferably carried out in aqueous solution and mostpreferably using water soluble salts of the monomers, eg: at a pHgreater than 5 especially 6 to 8. The preferred concentrations of thereagents in the reaction mixture is typically 50 to 80% by weight totalsolids especially 50 to 70%. The reaction, like the preparation of theintermediate requires a free radical source such as hydrogen peroxideand preferably elevated temperatures, eg: 40 to 100° C.

[0029] At the higher concentrations higher temperatures, eg: 100 to 140°C. more preferably 120 to 140° C. may be required to maintain a pourablesolution. The molecular weight of the product is typically up to200,000. Usually the number of monomer groups per molecule is from 1 to500, eg: 10 to 100. To prepare the telomers we prefer pH between 2 and 9especially 2 to 6, eg: 2.5 to 4.

[0030] We do not exclude the presence of water miscible solvents. Thesolvent should contain sufficient water to dissolve the reagents to asubstantial extent. The organic solvent may for example comprisemethanol, ethanol, isopropanol, ethylene glycol, propylene glycol, awater soluble oligomer of ethylene or propylene glycol such asdiethylene glycol, a water soluble mono or di ether or ethylene glycolmonomethyl ether, ethylene glycol dimethyl ether, diethylene glycolmonoethyl ether or diethylene glycol mono methyl ether, glycerol, awater soluble glyceryl ether, acetone, and/or dioxan. The requirement todissolve the reagents in the same aqueous based solvent is the mainlimitation on choice of unsaturated reagent. In cases of difficulty itmay be possible to carry out the reaction in anhydrous dioxan.

[0031] The reaction may optionally be carried out in a stream of aninert gas such as nitrogen.

[0032] The reaction may be carried out batch-wise, semi-continuously orcontinuously, eg: in a pipe reactor. The free radical source may all beadded initially or, preferably, in a plurality of additions, orcontinuously or semi-continuously throughout the reaction. To maximisethe yield of phosphonated product it is sometimes necessary to add theunsaturated reagent, continuously or intermittently during the reactionperiod to an aqueous solution of the phosphinate.

[0033] The products especially telomers comprising acrylate and/ormaleate and/or proportions, usually minor, or vinyl sulphonate, vinylphosphonate and/or vinylidine diphosphonate are valuable as corrosioninhibitors and scale inhibitors in the treatment of water systemsincluding boiler water, cooling water, eg: in evaporative coolingsystems, process water, water in central heating and air conditioningsystems.

[0034] The products are effective in the presence of chlorine, chlorinedioxide, bromine, hypochlorite, hypobromite and other oxidisingbiocides. They are useful in treatment of desalination plant and fortreating water used or produced in oil wells including injection water,produced water and water used for hydrostatic testing of pipelines.

[0035] The product are also effective as a “smut” inhibitor or sealantin the anodising of aluminium, as additives to oral hygiene preparationsand dentifrices and as a setting retarder for cement or plaster.

[0036] The products also find application as deflocculants ordispersants for particulate inorganic substances (such as clays andcalcium carbonate) and for other pigments, for cement and for soils indetergency.

[0037] The products are also effective as corrosion inhibitors forferrous and non-ferrous metals (e.g. aluminium or galvanised steel) andas a surface treatment for aluminium in the preparation of lithographicplates.

[0038] They are also of value as detergent builders or auxiliarybuilders, eg: in conjunction with zeolites, or as metal chelatingagents, eg: in metal extractions.

[0039] The products are effective for the inhibition of scale caused bymetal carbonates and basic carbonates (particularly those of metals ofGroup IIA of the Periodic Classification), as well as scale caused bycarboxylates, fluorides, hydroxides, phosphates, phosphonates, silicatesand sulphates.

[0040] They may be used in aqueous based functional fluids such ashydraulic fluids, lubricants, cutting fluids and oilfield drilling muds.

[0041] In particular, the telomers of the invention may be used insqueeze treatment of oil wells. They are especially effective inpreventing barium sulphate scale. For example in oil wells the hole istypically flushed out with aqueous surfactant to provide a waterwettable surface and then impregnated with a solution of the inhibitor.The calcium salt may be formed in situ either by calcium in theformation, where the latter comprises limestone, or by prior, orsubsequent, treatment of the hole with an aqueous calcium salt, eg:where the formation comprises sandstone.

[0042] Effective concentrations may typically range from 1 to 200 ppm,eg: 1.5 to 20 ppm, most preferably 2 to 10 ppm, may give usefulcorrosion protection. However, for oilfield scale prevention wherebarium sulphate is a problem, concentrations in the range 5 to 200,especially 8 to 25, eg: 10 to 20 ppm, are preferred.

[0043] Products according to the invention may be used in combinationwith one another, and/or in conjunction with other water treatmentagents including: surfactants, such as anionic surfactants (eg: C₁₀₋₂₀alkyl benzene sulphonates, C₁₀₋₂₀ olefin sulphonates, C₁₀₋₂₀ alkylsulphates, C₁₀₋₂₀ alkyl 1 to 25 mole ether sulphates, C₁₀₋₂₀paraffinsulphonates, C₁₀₋₂₀ soaps, C₁₀₋₂₀ alkyl phenol sulphates,sulphosuccinates, sulphosuccinamates, lignin sulphonates, fatty estersulphonates, C₁₀₋₂₀ alkyl phenol ether sulphates, C₁₀₋₂₀ alkylethanolamide sulphates, C₁₀₋₂₀ alpha sulphofatty acid salts, C₁₀₋₂₀ acylsarcosinates, isethionates, C₁₀₋₂₀ acyl taurides, C₁₀₋₂₀ alkyl hydrogenphosphates), non-ionic surfactants (eg: ethoxylated material orsynthetic C₈₋₂₅ alcohols, ethoxylated fatty acids, ethoxyl/propyleneoxyblock copolymers, ethoxylated fatty amines, mono- and di-alkanolamides,amine oxides and C₁₀₋₂₀ acyl sorbitan and/or glyceryl ethoxylates)amphoteric surfactants (eg: betaines, sulphobetaines, and/or quaternisedimidazoline), and/or cationic surfactants (eg: benzalkonium salts,C₁₀₋₂₀ alkyl trimethyl ammonium salts, and/or C₁₀₋₂₀ alkyl trimethyl ortris(hydroxymethyl) phosphonium salts); sequestrants, chelating agents,corrosion inhibitors and/or other threshold agents (eg: sodiumtripolyphosphate, sodium ethylenediamine tetracetate, sodium nitrilotriacetate, tetra potassium pyrophosphate, acetodiphosphonic acid andits salts, ammonium trismethylene phosphonic acid and its salts,ethylenediamine tetrakis (methylene phosphonic) acid and its salts,diethylenetriamine pentakis (methylene phosphonic) acid,hexamethylenediamine tetrakis (methylene phosphonic) acid,bishexamethylenetriamine pentakis (methylene phosphonic) acid andethanolamine bis(methylenephosphonic) acid and its salts); tolyltriazoleand mixtures of nitrate, benzoate, HHP and/or PTCB) biocides (eg:tetrakis (hydroxymethyl) phosphonium salts, formaldehydeglutaraldehyde); oxidising biocides and/or bleaches (eg: chlorine,chlorine dioxide, hydrogen peroxide, sodium perborate); foam controllingagents such as silicone antifoams, acetylenic diols; oxygen scavengerssuch as hydrazines and/or hydroxylamines; pH controlling and/orbuffering agents such as amines, borates citrates and/or acetates;chromium salts; zinc salts; and/or other water treatment agents such aspolymeric dispersants and coagulants including polymaleic, polyacrylicand polyvinylsulphonic acids and their salts, starches and/or carboxymethyl cellulose and/or molybdates. The invention provides formulationscomprising an effective amount of a product of the invention asaforesaid and any of the aforesaid known water treatment agents. Suchformulations may, for example, contain from 5 to 95% by weight of aproduct of the invention and from 5 to 90% by weight of one or more ofany of the aforesaid water treatment agents.

[0044] According to a further embodiment our invention provides acorrosion inhibiting pigment which is a solid composition which may beprepared by reacting a concentrated aqueous solution of any of the watersoluble telomers according to the invention with a base or salt ofcalcium, zinc, barium, aluminium or other polyvalent metal andprecipitating a solid salt.

[0045] According to a further embodiment our invention provides acorrosion inhibiting coating composition containing a pigment accordingto the invention.

[0046] The corrosion inhibiting pigment may be dissolved or dispersed inan anti corrosive paint, varnish, enamel, lacquer, or other coatingformulation. The formulation may comprise a volatile liquid vehicle,such as water or a volatile organic solvent including petroleum spirit,turpentine, ketones, esters and/or aromatic hydrocarbon solvent, and/ora drying oil, such as linseed oil, soya oil, tung oil or dehydratedcastor oil, which may optionally be dissolved in said volatile organicsolvent or emulsified in said water.

[0047] The formation typically may also comprise a resin, eg: polyester,urea formaldehyde, melamine, acrylic, alkyd, polyurethane, vinylchloride, vinyl acetate, phenolic or epoxy resin dissolved or dispersedtherein and/or a dispersed pigment. We prefer that the pigment should beor should comprise other corrosion inhibiting pigments such as red lead,potassium zinc chromate, metallic zinc or aluminium powder or zinc oxideand/or that the formulation should contain one or more of the othercorrosion inhibitors referred to above in addition to the corrosioninhibiting pigment of the invention.

[0048] The coating compositions may additionally contain any of theconventional paint ingredients, including pigments such as titaniumoxide, iron oxide, carbon black, phthalocyanine pigments or aluminiumstearate, chlorinated rubber, polystyrene, silicone, asphalt, wettingagents, dispersants, emulsifiers, biocides, flocculants, marineantifoulants, antifoams, viscosifiers, fire retardants, fluorescers,aerosol propellants, talc, clay and/or plasticisers.

[0049] Alternatively the water soluble corrosion inhibitors of theinvention may be used to provide a corrosion inhibiting treatment formetal surfaces such as steel, aluminium and aluminium alloys after anymachining and prior to storage, coating, electroplating, polishing oretching. Typically the work is coated with an aqueous solutioncontaining at least an operative amount of said corrosion inhibitor, eg:10 to 500 ppm preferably 25 to 300, eg: 20 to 200 especially 25 to 100,more especially 30 to 80.

[0050] After contacting with the corrosion, inhibiting solution the workmay be rinsed and/or subjected to one or more coating or finishingoperations such as resin coating, lacquering, enamelling, painting,electrophoretic coating, spattering, vapour deposition,electrodeposition, etching, chemical or electrical polishing or may beput aside for storage.

[0051] The work may be greased for storage, but an advantage of thetreatment is that greasing and hence subsequent degreasing may beavoided.

[0052] The product may be incorporated into solid or liquid detergentcompositions. It functions as a stain remover and also may help tostabilise any bleach present and exhibits valuable detergent buildingaction by sequestering calcium. Typically it is added to detergentcompositions in amounts of from 0.5 to 20% by weight of the composition.The liquid detergent of our invention preferably contains 5 to 50%, eg:10 to 40% by weight surfactant, 5 to 60%, eg: 10 to 40% builder, 20 to75%, eg: 50 to 70% by weight water and 0.1 to 2.5% of said polymer. Theliquid detergent preferably also contains conventional amounts of minoradjuncts including enzymes, soil suspenders such as sodium carboxymethylcellulose, optical brighteners, dyes, perfumes, preservatives and foammodifiers.

[0053] The builder preferably comprises non-phosphate builders such aszeolite, carbonate, citrate, nitrilotriacetate and ethylene diaminetetracetate.

[0054] The detergent formulations of the invention may contain from 1 to90% by weight of surfactant, more usually 2 to 70%, eg: 3 to 60%especially 4 to 50%, preferably 5 to 40%, more preferably 6 to 30%, mostpreferably 7 to 20%.

[0055] For example the surfactant may be, or may comprise, one or moreanionic surfactants such as an alkyl benzene sulphate, alkyl sulphate,alkyl ether sulphate, paraffin sulphonate, olefin sulphonate, alkylether sulphonate, alkylphenyl sulphate, alkylphenyl ether sulphate,alkyl sulphosuccinate, alkyl sulphosuccinamate, alkyl isethionate, alkylsarcosinate, soap, alkyl ether carboxylate, alkyl ether polycarboxylate,alkyl tauride, alkyl phosphate, alkyl ether phosphate or alkyl or thiolcapped polyelectrolytes such as an alkylthiol capped polymaleic acid.

[0056] All references to “alkyl” groups in this context refer to C₈₋₂₂straight or branched chain alkyl or alkenyl groups. “Ether” refers toglyceryl, mono or poly ethylenoxy, mono or poly propyleneoxy. The cationof the aforesaid anionic surfactants is usually sodium but may bepotassium or mono, di or tri alkylolamine. Less commonly the cation may,be lithium, ammonium, calcium, magnesium, zinc or a mono, di or trialkyl amine such as isopropylamine or trimethylamine.

[0057] The surfactant may also be, or may comprise, one or morenon-ionic surfactants such as the polyalkoxylated derivatives ofalcohols carboxylic acids, alkyl phenols, alkylamines, alkanolamides, orglycerol or sorbitan ester, wherein each compound has an “alkyl” groupas hereinbefore defined, and the polyalkylene oxy group comprises from 1to 50, eg: 2 to 10 ethylene oxy groups.

[0058] The invention is illustrated by the following examples:

EXAMPLE 1

[0059] To a 1 litre round bottomed flask was added 132 g ofhypophosphorous acid (50% w/w) and 1,4-dioxane (500 g), the mixture washeated under reduced pressure on a rotary evaporator to co-evaporatesome of the water from the hypophosphorous acid. In total, 233 g ofsolvent were removed and this was replaced with 1,4-dioxane.

[0060] The solution from above was added to a 1 litre jacketed reactorfitted with a reflux condenser, temperature probe, gas sparge tube,outlet bubbler, oil circulator and overhead stirrer, and left under agentle nitrogen sparge overnight.

[0061] The reaction mixture was heated to 70° C. and 2 g of freshazoisobutyronitrile (AIBN) was added as the acetylene addition wasstarted. Further 2 g portions were added every hour for 4 hours, afterwhich the reaction was left to cool to room temperature and sparged withnitrogen for 16 hours, giving a 61% conversion to product.

[0062] A further 4 hours of acetylene addition with 2 g AIBN being addedevery hour resulted in a 68% yield of product; this was increased to 72%when sodium persulphate was added at a rate of 1 g per hour for 5 hours.At this point the reaction was concluded as being complete and was leftto cool to room temperature under a nitrogen atmosphere. The productseparated into two phases. Residual 1,4-dioxane was removed on therotary evaporator and the product was diluted with water to 25% w/w.

[0063] Composition

[0064] Ethane 1,2-bis phosphinic acid 45.7% w/w

[0065] Diethylene triphosphinic acid 28.3% w/w

[0066] Hypophosphorous acid 18.6% w/w

[0067] Phosphate 7.7% w/w

EXAMPLE 2

[0068] To a 1 litre jacketed reactor fitted with a reflux condenser,temperature probe, oil circulator, overhead stirrer, and two peristalticpumps was added 32.2 g of the reaction product of Example 1. Thereaction mixture was heated to 78° C. after which the following twoseparate feeds were started at the same time:

[0069] 1) 9 g of sodium persulphate in water 100 g

[0070] 2) 72 g of acrylic acid in water (270 g) adjusted to pH4 withsodium hydroxide (46-48% w/w) and 32.2 g of the product of example 1.

[0071] The solutions were fed for 150 minutes and the temperature wassteadily increased to 96° C. After the two feeds were complete they wereimmediately replaced with a further two feeds:

[0072] 1) 9 g of sodium persulphate in water 100 g

[0073] 2) 72 g of acrylic acid in water (270 g) adjusted to pH4 withsodium hydroxide (46-48% w/w).

[0074] The solutions were fed for 150 minutes and the temperature wasmaintained between 96 and 101° C. After the two feeds were complete thereaction mixture was left to stir for a further 60 minutes before beingleft to cool to room temperature. The product was a pale yellow solution(962 g), 98% conversion to polymeric products by ³¹P NMR. GPC gave amolecular weight of 3650 g.

EXAMPLE 3

[0075] The product of Example 2 was tested in tube blocking tests asfollows: Test Conditions Test Temperature 121° C. Test Medium Asynthetic Produced Water corresponding to a 50:50 mix of FormationWater:Sea Water and having the following composition IONIC COMPOSITION(mg/l) ION Formation Water Sea Water Produced Water Na⁺ 24100 1089017495 K⁺  1180  460  820 Ca²⁺  520  428  474 Mg²⁺   73  1368  720 Ba²⁺ 650   0  325 Sr²⁺   55   7   31 Cl⁻ 40400 19766 30083 SO₄ ²⁻   10  2960 1485 HCO₃ ⁻   0  140   70 Test pH The pH value is adjusted to 4.90 ±0.05 @ 25° C. with 0.01 M acetic acid/sodium acetate buffer. InhibitorThe run starts with an initial inhibitor level of 100 mg/l Concentration(active acid) in the combined flow and decreases the concentration in 10mg/l steps, with a complete tube cleaning and washing cycle beingperformed between each decrement. Cycle Time Each level of inhibitor isevaluated for 30 minutes before proceeding to the next, ie: lower evel.The pressure drop across the narrow bore coil is continuously monitoredand logged by a personal computer running Advantech ® ‘Genie’ ™ dataacquisition and control software. Fail Criterion & In the absence ofinhibitor and under these conditions, MIC the tube becomes rapidlyblocked with scale. In practice, to prevent complete and irrecoverableblockage of the tube, the brine flows are terminated and tube cleaningcommences when the pressure drop reaches 1 psia. When evaluatinginhibitors, if the pressure drop exceeds 1 psia within the 30 minutescycle time, then the inhibitor is deemed to have failed at that level.The minimum inhibitory concentration, MIC therefore obviously liessomewhere between the “fail level” and the previous concentration atwhich the tube remained essentially clear for 30 minutes.

[0076] The product was effective at preventing tube blocking atconcentrations down to between 80 and 90 ppm. This compares well withthe best commercial oilfield scale inhibitors.

EXAMPLE 4

[0077] To a 250 ml 3-necked flask fitted with a reflux condenser,temperature probe and N₂ gas line was added 25 g sodium hypophosphite(0.7 mol H₂O), propargyl alcohol (14 g) and water (20 ml). Sodiumpersulphate (6 g) was dissolved with water (20 ml).

[0078] The reaction mixture was heated to reflux (approximately 101° C.)under an inert atmosphere and the initiator was steadily added through aperistaltic pump over 105 minutes, followed by a 30 minute age.

[0079] A further portion of initiator (6 g in 20 ml water) was addedover 90 minutes followed by a 30 minute age. Analysis by ¹³C-NMR showedresidual propargyl alcohol remained.

[0080] The reaction mixture was diluted with water (20 ml ) to dissolveup the undissolved solids, a further portion of initiator (6 g in 20 mlwater) was added over 90 minutes followed by a 30 minute age, afterwhich the reaction was left to cool to room temperature.

[0081] Yield 150 g, 4% Actives. Composition ³¹P-NMR shows Polymericproduct 83.7% w/w Phosphorous acid 11.4% w/w Phosphate  2.7% w/w Sodiumhypophosphite  2.2% w/w

[0082]¹³C-NMR shows all propargyl alcohol reacted.

[0083] GPC gives MW of 1624: therefore “n” can be calculated as being10.7.

EXAMPLE 5

[0084] To a 11, four-necked flask fitted with a reflux condenser,temperature probe and N₂ gas line was added 107 g sodium hypophosphite(0.7 mol H₂O) propargyl alcohol (60 g) and water (85 ml). Sodiumpersulphate (26 g) was dissolved in water (85 ml).

[0085] The reaction mixture was heated to reflux (approximately 101° C.)under an inert atmosphere and the initiator was steadily added through aperistaltic pump over 120 minutes, followed by a 60 minute age.

[0086]³¹P-NMR showed 41% sodium hypophosphite remained.

[0087] A further portion of initiator (26 g in 85 ml water) was addedover 90 minutes followed by a 60 minute age.

[0088] The reaction mixture was diluted with water (100 ml) to dissolveup the undissolved solids and was left to cool to room temperature.

[0089] Yield 564 g, 27% Actives. Composition ³¹P-NMR shows Polymericproduct 84.1% w/w Phosphorous acid  6.3% w/w Phosphate  0.6% w/w Sodiumhypophosphite   9% w/w

[0090] CPC gives MW of 1139, therefore “n” can be calculated as being7.3.

EXAMPLE 6

[0091] The product of example 4 was tested as a corrosion inhibitor ofmild steel in South Staffordshire water. The corrosion rate was lessthan 0.2 mils per year when the product was used at a concentration of25 ppm.

1. A compound of the formula (I)

wherein: R and R′ are each independently selected from hydrogen, ahydroxyl group, a carboxyl group, an alkyl, aryl or alkaryl group or ahydroxy- or carboxy-substituted alkyl, aryl or alkaryl group, providedthat R and R′ together have a total of less than 23 carbon atoms; R″ ishydrogen, or CHR═CR′ or selected from the same categories as R′″; R′″ isa group, or a polymeric chain comprising from 1 to 100,000 groups, eachsaid group being derived from at least one ethylenically unsaturatedcompound wherein the double bond is activated by an adjacentelectron-withdrawing group; X is hydrogen or a cation or an alkyl groupand n is greater than
 1. 2. A method of producing a compound accordingto claim 1, said method comprising the co-polymerisation ofhypophosphorous acid or a salt or ester of said acid with an acetyleniccompound of formula RC≡CR′, where R and R′ (which may be the same ordifferent) are each selected from hydrogen, a hydroxyl group, a carboxylgroup, an alkyl, aryl or alkaryl group or a hydroxy- orcarboxy-substituted alkyl, aryl or alkaryl group having from 1 to 22carbon atoms, so that R and R′ together have from 0 to 25 carbon atoms,whereby in said formula (I) R″ and R′″ are each hydrogen and the averagevalue of n is greater than one.
 3. A method according to claim 2, inwhich said co-polymerisation is carried out in a solvent capable ofdissolving both said hypophosphorous acid or salt and said acetylericcompound and in the presence of an initiator.
 4. A method according toclaim 3, in which said solvent is water.
 5. A method according to claim3, in which said solvent is a polar organic solvent.
 6. A methodaccording to claim 5, in which said solvent is ethanol, dioxan, awater-miscible glycol or glycol ether, a ketone or dimethyl formamide.7. A method according to any one of claims 3 to 6, in which saidinitiator comprises a source of free radicals.
 8. A method according toclaim 7, in which said initiator comprises hydrogen peroxide, sodiumpersulphate, an azo-compound or an organic peroxide.
 9. A methodaccording to any one of claims 3 to 6, in which said initiator comprisesa source of ultraviolet or ionising radiation.
 10. A method according toany one of claims 2 to 9, in which said acetylenic compound isacetylene.
 11. A method according to any one of claims 2 to 9, in whichsaid acetyleric compound is an alkyne, a hydroxy-alkyne or acarboxy-alkyne having from 3 to 25 carbon atoms.
 12. A method accordingto claim 11, in which said acetylenic compound is propargyl alcohol,acetylene dicarboxylic acid, 1-butyne, 2-butyne, a C₁₂-C₁₄ alkyne or acyclic alkyne.
 13. A method according to any one of claims 2 to 12, inwhich said co-polymerisation is carried out at a temperature of from 40to 100° C.
 14. A method according to claim 13, in which said temperatureis from 50 to 70° C.
 15. A method according to any one of claims 2 to14, in which both of said co-monomers are present in substantially equalproportions.
 16. A method according to any one of claims 2 to 14, inwhich either of said co-monomers is present in a stoichiometric excessof up to 20% relative to the other co-monomer.
 17. A method according toclaim 16, in which said hypophosphorus acid co-monomer is present in astoichiometric excess of up to 20% relative to said acetylenicco-monomer.
 18. A method according to any one of claims 2 to 17, inwhich said salt of hypophosphorous acid is the sodium, potassium orammonium salt.
 19. A method according to any one of claims 2 to 17, inwhich said ester of hypophosphorous acid is the methyl, ethyl orisopropyl ester.
 20. A compound according to claim 1, said compoundcomprising a polymer of the formula (II):

wherein X has the same significance as in claim 1 and n is in the range1.05 to
 100. 21. A compound according to claim 20, in which n is in therange 1.2 to
 50. 22. A compound according to claim 20 or 21, in which nis in the range 1.5 to
 25. 23. A compound according to claim 20, 21 or22, in which n is in the range 2 to
 20. 24. A compound according to anyone of claims 20 to 23, in which n is in the range 3 to
 15. 25. Acompound according to claim 1 and to any one of claims 20 to 24, saidcompound comprising a telomer of the formula (III):

wherein X, R and R′ have the same significance as in claim 1, at leastone R^(v) in each monomer unit is selected from hydroxy, carboxy,sulpho, phosphono, amido, aceto and aryl groups or halogen; each otherR^(v) is independently selected from hydrogen, C₁₋₄ alkyl, carboxyl,sulpho, phosphono and hydroxyl groups or carboxy-, sulpho-, phosphono-or hydroxy-substituted C₁₋₄ alkyl groups; (a+b) is in the range 5 to 200and n is greater than
 1. 26. A method of producing a telomer accordingto claim 25, said method comprising co-polymerising a polymer accordingto any one of claims 20 to 24 with at least one monomer of formula R₂^(v)═CR₂ ^(v), wherein R^(v) has the same significance as in claim 25,in the presence of a free-radical initiator.
 27. A method according toclaim 26, in which said at least one monomer is selected from acrylicacid, fumaric acid, maleic acid, vinylsulphonic acid, vinyl phosphonicacid, vinylidene diphosphonic acid, methacrylic acid, itaconic acid,aconitic acid, mesaconic acid, citraconic acid, crotonic acid,isocrotronic acid, angelic acid, tiglic acid and the water-soluble saltsof said acids.
 28. A method according to claim 26 or 27, in which therelative proportions of said polymer and said at least one monomer arein the range 1:1 to 1:1000.
 29. A method according to claim 28, in whichsaid relative proportions are in the range 1:5 to 1:500.
 30. A methodaccording to claim 28 or 29, in which said relative proportions are inthe range 1:10 to 1:100.
 31. A method according to claim 28, 29 or 30,in which said relative proportions are in the range 1:15 to 1:50.
 32. Amethod according to any one of claims 26 to 31, in which saidco-polymerisation is carried out in aqueous solution.
 33. A methodaccording to claim 32, in which said co-polymerisation is carried out inthe presence of a water-miscible solvent.
 34. A method according toclaim 33, in which said water-miscible solvent comprises methanol,ethanol, isopropanol, ethylene glycol, propylene glycol, diethyleneglycol, ethylene glycol monomethyl ether, ethylene glycol dimethylether, diethylene glycol monomethyl ether, glycerol, a water-solubleglyceryl ether, acetone and/or dioxan.
 35. The use of a compoundaccording to claim 1 or to any one of claims 20 to 25 as a corrosioninhibitor and/or scale inhibitor in the treatment of a water system. 36.Use according to claim 35, in which said water system comprises boilerwater, cooling water, process water, oil field water, injection water,produced water and water used for hydrostatic testing of pipelines. 37.Use according to claim 35 or 36 in the squeeze treatment of oil wells.38. The use of a compound according to claim 1 or to any one of claims20 to 25 as a “smut” inhibitor or sealant in the anodising of aluminium.39. The use of a compound according to claim 1 or to any one of claims20 to 25 as an additive to oral hygiene preparations and dentifrices.40. The use of a compound according to claim 1 or to any one of claims20 to 25 as a cement or plaster setting retarder.
 41. The use of acompound according to claim 1 or to any one of claims 20 to 25 as adeflocculant or dispersant for particulate inorganic substances.
 42. Theuse of a compound according to claim 1 or to any one of claims 20 to 25as a detergent builder or auxiliary builder.
 43. The use of a compoundaccording to claim 1 or to any one of claims 20 to 25 as a surfacetreatment in the preparation of lithographic plates.
 44. A corrosioninhibiting pigment comprising the reaction product of a telomeraccording to claim 25 and a base or a salt of calcium, zinc, barium,aluminium or other polyvalent metal.
 45. A corrosion inhibitingcomposition containing a pigment according to claim 44.